Mapping Mountains – Summit Relocations – Y Trichant

Mynydd y Grug (ST 177 906)

There has been a Summit Relocation to a hill that is listed in the Y Trichant, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Mynydd y Grug (ST 177 906)

The criteria for the listing that this summit relocation applies to are:

Y Trichant – Welsh hills at or above 300m and below 400m in height with 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13^th May 2017.

The name of the hill is Mynydd y Grug and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A469 road to its west, the B4251 and the Afon Sirhywi (Sirhowy River) to its north-east and the A468 road to its south, and has the town of Caerffili (Caerphilly) towards the south-west.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 348m summit height, based on the spot height positioned at ST 17688 90958 that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating; Workings probably obliterated 350c top at ST176908 on 1986 1:50000 map.  As heights on 1:25,000 scale mapping were prioritised in this list over those on 1:50,000 scale mapping this hill’s summit was listed to where the 348m spot height appears on the 1:25,000 Explorer map.

Extract from the old Ordnance Survey 1:25,000 Explorer map

Extract from the contemporary Ordnance Survey 1:50,000 Landranger map

The details for this hill were re-assessed when the Ordnance Survey Vector Map became available online and this shows a 375m summit spot height with contemporary Ordnance Survey 1:25,000 Explorer maps showing an uppermost 370m ring contour and a raised summit area which is the bi-product of mine waste spoil.

Extract from the contemporary Ordnance Survey 1:25,000 Explorer map

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR summit image of Mynydd y Grug

The summit height produced by LIDAR analysis and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by LIDAR analysis is 374.2m and is positioned at ST 17753 90669, this position is given a 375m spot height on the contemporary Ordnance Survey Vector map and is approximately 275 metres south south-eastward from the previously listed summit position where the 348m spot height appears on the Ordnance Survey 1:25,000 Explorer map.  

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Mynydd y Grug

OS 1:50,000 map:  171

Summit Height:  374.2m (LIDAR)

Summit Grid Reference (new position):  ST 17753 90669 (LIDAR)

Bwlch Height:  169.85m (LIDAR)

Bwlch Grid Reference:  ST 16783 95144 (LIDAR)

Drop:  204.3m (LIDAR)

Myrddyn Phillips (July 2019)

Mapping Mountains – Summit Relocations – Y Trichant and Y Trechol – The Dominant Hills of Wales

Mynydd y Lan (ST 209 923)

There has been a Summit Relocation to a hill that is listed in the Y Trichant and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Mynydd y Lan (ST 209 923)

The criteria for the two listings that this summit relocation applies to are:

Y Trichant – Welsh hills at or above 300m and below 400m in height with 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13^th May 2017.

Y Trechol – The Dominant Hills of Wales – Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The name of the hill is Mynydd y Lan and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is encircled by roads with the B4251 to its south and west, the A472 to its north and the A467 and B4591 and the Afon Ebwy (Ebbw River) to its east, and has the town of Trecelyn (Newbridge) towards the north and the village of Pontycymer (Crosskeys) towards the east.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 381m summit height, based on the spot height positioned at ST 20794 92508 that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating that the Ordnance Survey 1:50,000 Landranger map has a 385m spot height positioned at ST 20898 92357.  As heights on 1:25,000 scale mapping were prioritised in this list over those on 1:50,000 scale mapping this hill’s summit was listed to where the 381m spot height appears on the 1:25,000 Explorer map.

Extract from the Ordnance Survey 1:25,000 Explorer map

Extract from the Ordnance Survey 1:50,000 Landranger map

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the Vector Map Local hosted on the Geograph website, and which is entitled the Interactive Coverage Map, and in the case of this hill it is the series of Ordnance Survey Six-Inch maps where the origins of the 385m spot height that appears on the 1:50,000 Landranger map can be traced, as the Six-Inch map surveyed in 1875 and published in 1885 has a 1263.6ft (385.15m) surface height at the same position as the contemporary 385m spot height.

Extract from the Ordnance Survey series of Six-Inch maps

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

LIDAR summit image of Mynydd y Lan

The summit height produced by LIDAR analysis and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by LIDAR analysis is 381.3m and is positioned at ST 20903 92337, this position is given a 385m spot height on contemporary Ordnance Survey 1:50,000 Landranger maps and is approximately 200 metres south south-eastward from the previously listed summit position where the 381m spot height appears on the Ordnance Survey 1:25,000 Explorer map.  

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Mynydd y Lan

OS 1:50,000 map:  171

Summit Height:  381.3m (LIDAR)

Summit Grid Reference (new position):  ST 20903 92337 (LIDAR)

Bwlch Height:  159.5m (LIDAR)

Bwlch Grid Reference:  ST 19806 96725 (LIDAR)

Drop:  221.8m (LIDAR)

Dominance:  58.17% (LIDAR)

Myrddyn Phillips (July 2019)

Mapping Mountains – Summit Relocations – Y Trichant

Cefn Llanbister (SO 116 733)

There has been a Summit Relocation to a hill that is listed in the Y Trichant, and which was initiated by LIDAR analysis and confirmed by a survey with the Trimble GeoXH 6000, both of which were conducted by Myrddyn Phillips, with the latter taking place on the 03.07.18 in warm and clear conditions.

Cefn Llanbister (SO 116 733)

The criteria for the list that this summit relocation applies to are:

Y Trichant – Welsh hills at or above 300m and below 400m in height with 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and its renaming appearing on Mapping Mountains on the 13^th May 2017.

The name of the hill is Cefn Llanbister and it is placed in the Beacon Hill group of hills, which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the Afon Ieithon (River Ithon) and the A 483 road to its west and the B 4356 road to its north, and has the small community of Llanbister at its base to the west of the summit.

As the summit of the hill is a part of open access land it can be approached from most directions with public footpaths accessing this land from the west and east, with the most convenient access to the hill via a track that leaves the B 4356 road just to the north of the summit.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 373m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating 376m at SO GR117732 on 1986 1:50000 map.

Extract from the Ordnance Survey 1:25,000 Explorer map

Prior to LIDAR analysis and the subsequent survey with the Trimble GeoXH 6000 the listed height of this hill had been revised to 376m based on the spot height on the Ordnance Survey 1:50,000 Landranger map.

Extract from the Ordnance Survey 1:50,000 Landranger map

The summit height produced by the Trimble GeoXH 6000 survey is 377.5m (converted to OSGM15) at SO 11690 73303 and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by the Trimble GeoXH 6000 survey is 377.5m (converted to OSGM15) and is positioned at SO 11690 73303, this position is not given a spot height on contemporary Ordnance Survey maps and is approximately 100 metres east from where the 376m spot height appears on the Ordnance Survey 1:50,000 Landranger map and 450 metres north-west from where the 373m spot height appears on the Ordnance Survey 1:25,000 Explorer map.   

The Trimble GeoXH 6000 gathering data at the summit of Cefn Llanbister which confirmed the summit relocation of this hill

The full details for the hill are:

Group:  Beacon Hill

Name:  Cefn Llanbister

OS 1:50,000 map:  136, 148

Summit Height:  377.5m (converted OSGM15)

Summit Grid Reference (new position):  SO 11690 73303

Bwlch Height:  335.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 12399 74601 

 

Drop:  42.2m (converted to OSGM15)

For details on the survey that relocated the summit position of this hill

Myrddyn Phillips (November 2018)

Mapping Mountains – Summit Relocations – Y Trichant

Ffridd Top Llety (SJ 089 167)

There has been a Summit Relocation to a hill that is listed in the Y Trichant and which was initiated by LIDAR analysis, with the summit height, its position and the drop of the hill confirmed by a survey with the Trimble GeoXH 6000, which was conducted on the 5^th April 2018.

LIDAR image of Bryn (on left) and Ffridd Top Llety (on right)

The criteria for the list that this summit relocation affects are:

Y Trichant – All Welsh hills at and above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub category entitled the Sub-Trichant consisting of all Welsh hills at and above 300m and below 400m in height that have 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips and the Introduction to the list and the re-naming and publication history was published on Mapping Mountains on the 13^th May 2017. 

The name of the enclosed land where the summit of this hill is situated is Ffridd Top Llety and this was derived from local enquiry, and the hill is adjoined to the Y Berwyn range of hills which are situated in the south-eastern part of North Wales (Region A, Sub-Region A4), and is positioned between the B 4393 road to its north and the B 4382 road to its west, and has the small community of Llanfihangel-yng-Ngwynfa towards the west.

Ffridd Top Llety (SAJ 089 167)

As the summit of the hill is not on designated open access land permission to visit should be sought, for those wishing to do so there are two public footpaths that cross the field where the summit is situated and which come within a few metres of its high point.

When this hill was originally listed in the Welsh P30 lists on Geoff Crowder’s v-g.me website it was by the name of Bryn and its 347m map heighted summit location given as SJ 085 169.  Since this hill was first listed the Ordnance Survey Interactive Coverage Map hosted on the Geograph website has become available online and this map shows a second 347m map heighted summit positioned at SJ 089 167. 

Gathering data at the summit of Ffridd Top Llety

These two summits and their respective connecting bylchau were analysed via LIDAR and surveyed with the Trimble GeoXH 6000.  The resulting summit data is given below:

Bryn

LIDAR:  346.239m at SJ 08501 16871

Trimble GeoXH 6000:  346.367m at SJ 08501 16870

Ffridd Top Llety

LIDAR:  346.619m at SJ 08997 16749

Trimble GeoXH 6000:  346.551m at SJ 08997 16748 

Therefore, the confirmation of the position of the relocated summit is at SJ 08997 16748 and this consists of closely cropped grass in an enclosed grazing field, this position is approximately 500 metres east south-eastward from where the previous prioritised 347m map heighted summit of Bryn is located.

The Trimble GeoXH 6000 gathering data at the summit of Bryn with the position of the relocated summit of Ffridd Top Llety in the background on the left

The full details for the hill are:

Group:  Y Berwyn

Summit Height:  346.6m (converted to OSGM15)

Name:  Ffridd Top Llety

OS 1:50,000 map:  125

Summit Grid Reference (New Position):  SJ 08997 16748  

       

Drop:  69.6m (converted to OSGM15)

For details on the survey that confirmed the summit relocation of this hill

Myrddyn Phillips (May 2018)

Mapping Mountains – Summit Relocations – Y Trichant and Y Trechol – The Dominant Hills of Wales

Upper Park (SJ 189 052)

There has been confirmation of a Summit Relocation to a hill that is listed in the Y Trichant and Y Trechol – The Dominant Hills of Wales, and which was initiated by a survey with the Trimble GeoXH 6000, with the survey that confirmed this summit relocation taking place on the 7^th January 2018.

The criteria for the two listings that this summit relocation affects are:

Y Trichant - Welsh hills at and above 300m and below 400m in height that have 30m minimum drop. 

Y Trechol - The Dominant Hills of Wales - These are the Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those addition Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The name of the hill is Upper Park and it is situated in the Carnedd Wen range of hills which are in the south-eastern part of North Wales (Region A, Sub-Region A4), and it is positioned between the A 458 road to its north and the A 483 road to its south-east, and has the town of Y Trallwng (Welshpool) to its north-east.

Upper Park (SJ 189 052)

As the summit of the hill is not on designated open access land and a part of a private estate permission to visit should be sought, for those wishing to do so there are a number of options for an ascent, all of which use tracks through forested plantations.

When this hill was originally listed in the Welsh P30 lists on Geoff Crowder’s v-g.me website the summit position was given as SJ 189 052, and although this six figure grid reference matches that of the position of the confirmed relocation, its position was to the 352m spot height that appears on the Ordnance Survey 1:25,000 Explorer map (SJ 18895 05292).

Two data sets were taken with the Trimble GeoXH 6000, the first at the high point of the hill which is in a deciduous plantation known as Crown Wood.  The second was taken to the high point of the adjacent field where the 352m spot height appears, these results are given below:

1^st survey, inside Crown Wood at high point of hill:  354.0m (converted to OSGM15)

2^nd survey, adjacent field where the 352m spot height appears:  352.4m (converted to OSGM15)

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website showing the summit position in relation to the spot height position

Therefore, the confirmation of the position of the relocated summit is at SJ 18980 05270 and this is ground within a deciduous wood, this position is approximately 100 metres east south-eastward from where the 352m spot height appears on the Ordnance Survey 1:25,000 Explorer map.

The full details for the hill are:

Group:  Carnedd Wen

Summit Height:  354.0m (converted to OSGM15)

Name:  Upper Park

OS 1:50,000 map:  125

Summit Grid Reference (New Position):  SJ 18980 05270 

        

Drop:  177.0m (converted to OSGM15)

Dominance:  49.998%

The Trimble GeoXH 6000 gathering data at the summit of Upper Park with the position of where the 352m spot height appears on the ground in the frosted field in the centre background of this photo

For details on the survey that confirmed the summit relocation of this hill

Myrddyn Phillips (February 2018)